I think it's going to be difficult to do this with the current structure of the data. If you are able to have a column called [Year] with 2 values, instead of a different column for each year, you can do something like the workbook attached.
You first need to create a calculated field that finds the Maximum value between the 2 years:
When used on the the view, make sure it's computed for each panel:
Notice we are also using a dual axis, which allows us to add color/text only to the difference bars. You may need to move the primary measure in front of the Max Value:
You can see the calculations for Color and Text on the workbook attached, but you can use them on the 2nd axis. Make sure they are also computed for each panel:
Hope this helps!
Difference_v10.2.twbx 2.3 MB